The state of the art software to search keywords in a sound stream, the Keyword Spotting Software, is a limited vocabulary recognizer working on input speech that may include other words not included in its vocabulary and records the time period in which the desired words are spoken. Keyword spotting technology is a kind of automatic speech recognition (ASR) technology. It can be applied in some situations with special specific request, where due to the speed, high detection rate or other special requests, the people certainly do not need the system to recognize the whole sentence, and do not need to understand the whole sentence, whereas only pay attention to these sentences that contain the specific part(s). Some target markets for this technology are as bellow:

• Broadcasting companies, journalists and news agencies
• Police and other security authorities
• Private security organizations
• Advertising agencies
• Speech database developers